Today's Challenge

https://leetcode.com/problems/longest-valid-parentheses/

Longest Valid Parentheses - LeetCode

스택을 이용한 LCS 구하는 문제.

class Solution:
    def longestValidParentheses(self, s: str) -> int:
        max_ans = 0
        st = [-1]
        for i in range(len(s)):
            if s[i] == '(':
                st.append(i)
            else:
                st.pop()
                if len(st) == 0:
                    st.append(i)
                else:
                    max_ans = max(max_ans, i-st[-1])
        return max_ans